Speech and other oral functions. Clinical and experimental studies with special reference to maxillary rehabilitation on osseointegrated implants.

The aims of this thesis were first to longitudinally investigate patients' opinions of their speech and other oral functions, evaluate some parameters of oral functions and speech production after treatment with a maxillary fixed prosthesis on osseointegrated implants (FPOI) and secondly to analyse normal Swedish [s] production. 21 consecutive selected patients rehabilitated with maxillary FPOI were studied over a 3-year period. The parameters of masticatory functions were clenching force, chewing efficiency, oral stereognosis and oral motor ability. With the aid of perceptual, acoustic, and model analysis the speech production with special reference to [s] was also longitudinally evaluated. The occlusal thickness perception (OTP) was estimated. In order to evaluate the usefulness of electropalatographic (EPG) and optoelectronic equipments in analysing speech production a multiple analysis of [s] production in varying contexts were made at four sessions. All subjects were very pleased with the oral rehabilitation. The chewing efficiency over time improved. The replacement of a complete denture with an FPOI in the upper jaw, resulted in to a progressive increase of chewing efficiency and clenching force, and a subjective improvement of oral function. Concerning OTP, a threshold level of 20 microns was recorded in the subjects with natural dentition, at 50 microns in FPOI subjects and 100 microns subjects with complete dentures. Time for identification of small test pieces as an expression of oral stereognostic ability (OSA) as well as number of errors decreased immediately after insertion of an FPOI compared to the edentulous condition. Assembly time in oral motor ability test (OMA) also decreased. A further improvement was found at the final examination 3-6 months after rehabilitation. After initial phonetic problems, 92% of the patients considered themselves free from speech problems at the 3 year follow-up. The patients' experience corresponded well with the judgements of both the expert and the non expert groups. Difficulties in pronouncing [s] were associated with decreased bite-force, number of occluding contacts, frontal width of the fixed prosthesis and tenderness at palpation of the masticatory muscles. No correlation between open or closed interdental spaces and deteriorated speech was found. In general, EPG and mandibular movement pattern were similar between sessions and the sound quality normal. However, when subjects wore the artificial palate for the first time the [s] groove was wide, the mandibular movement smaller and the [s] quality some what deteriorated. [s] in varying context had different tongue groove width but a similar high average mandibular position.